Apparatus for drying granular products



May 1, 1923. A 1,453,750

N. C. CHRISTENSEN APPARATUS FOR DRYING GRANULAR PRODUCTS Filed Ma rch 81921 2 Sheets-Sheet [NYE/VTUH 7M 6. W

- May 1, 1923.

1,453, 750 N. c. CHRISTENSE'N APPARATUS FOR DRYING GRANULAR PRODUCTSFiled- March 8, 1921 2 Sheets-Sheet 2 .F2 .15. j Z

' INVENTOR M C? Mir/)2 ATTORNEY .To allwhom it may comer n.-

Patented May 1, 1923.

UNITED, srATas ass st PATENT orsica.

- NIELS C. CHRISTEI Q'SEN, OESAL'J. LAKE (iITY, UTAH.

"LIP PARA?US F63 DRYING GBANULAR PRODUCTS.

Application filed March 8, 1921. Serial No. 450,679.

Be it known that I, NmLs C. CHRIsrnN- SEN, a citizen of the UnitedStates, residing at Salt Lake Cit in the county of Salt Lake and State'Utah, have invented certain new and useful Improvements in Ap-- paratusfor Drying Granular Products, of which the following is a specification.

- This invention relates'toiinprovements in methods and apparatus fordrying gran-"- ular products such aslwheat and other grains or granularmineral products. It is. particularly adaptable to the drying of sizedproducts, i. e., products in which the grams or particles are ofapproximately the samesize, but is useful for the treatment of allproducts which are granular in their. nature. It. is not applicable tothe treatment of fine material or to the treatment of a mixture ofcoarse and fine in which the fine is in such proportion as to fill thevoids between the coaser or, granular products.

The method of drying now' most com. monly used consists in dropping thematerial to be dried throu h'a current of air which is either cold as insome wheat driers now used or hot as is used in different forms of oreand coal driers, etc. The dro ping of the material to be dried, thr0ught e air current is accomplishedinitwo general ways,

either by dropping-the material down a shaft supplied with baflie's ordeflectors against an upward current of air as exempli,

fied in, some wheat driers, or by passing the material through arevolving substantially horizontal c linder supplied with lifting de'vices which ift the material as the drum revolves and drops it throughthe currentof hot air or furnace gases. In some forms of driers thedrying gases are merely passed over the surface 0 g which is stirred tobring different portions of the mass i'r'itocontact with the ases In allthese forms ofz'apparatus t e material to if dried dccupies a relativelysmall part of. he space in-the machines and is in intimate contact ormixture with the (1 ing glases must be used, as in drying wheat or 0ter. grains in tower driers in which case avery large and very highapparatus-and an extremely large volume of jat ordinary the mas ofmaterial mg gases but a small part. of the time and t ese. machines;therefore have-.a relatively smallcapacity in relation to'g their size.This is particularly true wheti' 'relatively coldfdry il speratur s ust11 y c011 siderable drying efiect. .In the case of such as wheat thedryin thus secured is only superficial and is submit to the changes inmoisture content of the air used in drying which may have practically nodrying effect at all durin rainstorms or periodsof high humidity. n allthese forms of' apparatus the material is subjected to considerableabrasion and bruising which. is detrimental to many products and alsoresults in the, formation of fines which are blown away in the dryinggases. i

Th's invention aims to overcome all these objections and disadvantagesby'the use of a new method of drying by which the capacity f. theapparatus per unit volume is very greatly increased, greater efiiciencyof drying b the gases is secured and practiv cally all ruising andabrasion of the material prevented and the temperature'of drying may beeasil regulated and controlled. This new met od consists in passin acurrent of drying granular materia 1. e., forcing the drying gas undersufficient pressure throu h the voids between the particles and thus vringing the gas through a bed of the s into intnnate-contactuw'ith-thejmdividua grains. This maybe done in a method of drying should preferablybe carried out in counter-current fashion.-

Myx preferred manner of utilizing this new method consists therefore inpassin the granular product to be dried downwar as a mass through avertical shaft and at the same time forcing the-d 'ngg'ases up throu hthe mass in the voidz between the granu ar products. In this wayra'cticall the entire drying apparatus is lled wit material to bedriedand this material is in the most intimate contact with the drying gasesduring the entire "time of passage through the apparatus. The apparatushas therefore a very large capacity per unit of volume: Due to the.intimate mixture of the sees and solids and their counter-current ow thedrying efliciency of the gases s no. I

would be practical with the methods of dry now in common use, due to thelow capacity of the apparatus using these methods.

To secure the'greatest eiliciency in using my method it isnecessary'that the flow of material downward through the dryin shaft andthe flow of drying gases upwar through the mass of material bepractically the form an continuous and uniform over the entire hori--zonta1= cross section of the mass of material in the shaft. To securethese conditions the material to be dried should be fed practis callycontinuously onto the upper part of the chargeand should be dischar edfrom the lower part of the charge at t e same rate, and the dischargefrom the bottom of the charge should be substantially uniform over thewhole bottom and the depth of Y the charge should be substantially thesame in all parts. The finer the granular particles,- the more exactlymust these conditions be met to secure good results. With coarsermaterial the depth ofthe charge need not be so exactly the same in allparts.

To secure these conditions in my method of drying, I use the type ofapparatus shown in the drawings which consists in general ofav'vertical'shaft, to contain the material to be dried with means forfeeding the material substantially continuously and at 'a uniform rate,into the top of the shaft and distributing it over the whole area of theshaft, and means for substantially continuously discharging the materialat auniform rate at the bottom and/uniformly over the entire bottom ofthe char e, and means for forcing d ing'gases u t rough the charge fromthe ttom to t e top. means for heating the ases to the desiredtemperature will be use in most cases as the volume of drying gas is sovery much less when it is 'warmas compared with cold gases that the costof warming the gases is much 'less than the cost of forcing the muchlarger v gases are intr volume of colder gases through the charge.

It'will be ap arent that many variations details of construction will bepossiblein an apparatus of this type.

The drawings show some of the forms of my apparatus which may be usedfor this 11 a on:

p 1is a verticalsection on "a fiameter Extraneous of a circular form oftheap aratus, Fig. 2 a

.plan'view of the same an using no mechanical discharge device. 1g.

Fig. 3 a horizontal section of the same just above the 7 shows avertical section of a type of the apparatus of which Fig. 8 is a partialplan View. Figs: 9 and 10 are enlarged sections of the discharge deviceor feeder which may be used in the form of apparatus shown in Figs. 1and 3,.and Figs. 11 and 12 enlarged sections of the discharge. device orfeeder which ma be used in the form of apparatus shown in igs. 4 and 5.Fig. 13 is a vertical ,section on line A-A of the plan views shown inFigs. 14 and 15 of m preferred form of a paratus. Figs. 16 an 17 show aform of istributing device which me. be used with the form shown in Fig.15, 16 beinga plan view and 17 a vertical sectionona-diameter-of 1g. 16.Fig. 18 is a vertical section of the simple apparatus for intermittentdrying.

As previously stated the preferred apparatus consists in general of avertical shaft (1) which may be square or rectangular or circular incross-section. The length of the 'shaft will depend on the depth of thechar used which willin turn depend on the time of drying and the natureof the charge. 'lhe'i lofiger the time required,

the longer. the 'shaft, and the-coarser the the charge is a dischargedevice or discharge and a suitable distributing device orrake (3) orfeed hopper (11) to keep the top of the charge level. At the bottomoffeeder (4) which maybe constructed in a number. of difierent ways. Thefunction of this feeder is to substantially continuously discharge thedried material uniformly over a the whole bottom of the charger Themeans used to cause the current of drying gas to flow up through thecharge may also be of difierent forms; In my preferred form the bottomof the shaft beneath the discharge feeder (4) is closed by a suitablehopper (5) or plate or housing (40) and hopper 5) as ownin Fi 1, 4; 13and 15 and the or closed space (7 under pressure throu h a'presshrepipe(8) and pass u throu h t e discharge "coder (4) and up throng the ucedinto this hopper' (5) j char e. The dischargehizpper (5) has a suitele-discharge spoutat its lower oint through which the dried roduct isdischarged. This spout should be ept filled in a portion of its lengthin-order to prevent touch the plates (23).

escape of the drying gases through it. Another method of passing thegases up through the charge consists in the use of stationary perforatedpipes (10) in the lower part of the shaft as shown in Figs. 6 and 7.These pipes are connected with the main pressure pipe (58) outside ofthe shaft and are so arranged that the dried product may flow downwardaround them and be discharged at sufiicient distance beneath the pipesto secure a uniform flow and discharge.

As noted the feeding device may consist of spouts (2) alone or a spoutand rotary feeder hopper (11) or a' spout (2) and suitable levelingdevices (3). The spouts alone may be used with coarse granularmaterialand the feeding (2) and leveling devices (3) with finer. material. Theexact form of this part of the apparatus will depend on the nature ofthe product and the shape of the shaft. With the circular forms as shownin Figs. 1, 6 and a rotating feed hopper (11') or spouts (2) and arotatingrake or levelling device (3) may be used. If desired thenecessary'levelling may be done by hand at suitable intervals. The formof the discharge device may vary with the shape of the shaft. In thecircular forms as shown in Figs. 1, 2, 3 and 9 it may consistof two setsof concentric circular plates, one set slightly above the other, boththe upper set (13) and the lower set (14) being stationary and staggeredso that the dried product cannot pass down throu h the annular openings(15) and (16).1nto the hopper. As shown the lower rings of the feeder(14) are beneath'the annular opening (15) between the upper rings sothat the dried product may flow through the upper openings (15) onto thelower rings (14). The material on these lower rings (14) is continuouslyremoved bythe plows (17) which project up through the annular rings(16). The plows are attached to the radial arms (18) which are attachedto the rotating shaft (19') to which the feed hopper (11) is alsoattached. Fig. 10 shows a rotary feederwhich is similar to the foregoingexcept that the plows (7 are attached to the .upperrings.

(13) and the lower rings rotate being supported by a suitable spider(20) which is attached to the central shaft (19). In the square form ofany apparatus a reciprocating discharge feeder'ofthe type shown in Figs.4, 5, and 11 may be used. This c0nsists of an upper set of stationaryparallel plates (21) separated byopenings (22). Beneath the upper set isa similar set of parallel plates (23) with openings (24) so arrangedthat the plates (23) are beneaththe openings (22) so that no driedproduct can flow into the hopper (5) beneath. In the middle of eachopening (22) is a'stationary vertical'plate extending down so as toalmost The plates'(23) are supported by the. beams (25) and movedbackward and forward by the rod (26) and eccentric (27) (or otherreciprocating device) so that the material on the plates (23) is pushedoff through the openings (24).

The discharge feeder shown.in Fig. 12 is forth on the lower plates bythe reciprocating device (26 and 27). As will be readily seen by the useof these feeders a substantially uniform discharge from the whole areaof the bottomof the charge is' secured and that the rate of downwardflow of the charge may be accurately regulated by the speed of thefeeder mechanism.

If it is necessary or desirable to secure a very uniform feed intothetop of the shaft (1) over the whole area of the shaft this may besecured byfeeding the material into the top of the shaft through afeeder similar to those described and shown in the foregoing and shownin Figs. 1, 3, 4 and 5, instead of by means of. leveling devices aspreviously described. I

Another type of discharge feeder, which is my preferred type for manypurposes, is shown in Figs. 7, 8 and 13, 14 and 15. This type of feederconsists ofan endless belt which is held in place on the two pulleys(30) and supported by the plate (31) beneath the charge. The part of thebelt on which the charge rests, which is supported by the plate (31), ispulled forward toward the discharge side or hopper by turning one (orboth) of the pulleys, preferably the one near the discharge, by applyingpowerto the pulley(or gear or sheave) (32). In order to secure a uniformdischarge over the whole.

bottom the transverse vertical distributing plates (33) are used. Theseextend across the charge above the belt and are arranged preferably atequal distances apart and the lower edges in a sloping plane, extendingfrom the rear edge (34) of the shaft at the level of the belt to theedge (35) of the d scharge opening in the front of the shaft.

In this way a layer of equal thickness is removed from each of thespaces (36) between the vertical plates (33), thus securing a similardischarge from the entire bottomof the charge. As shown in Fig. 15 thistype of discharge feeder may be used with a shaft of circular crosssection. In this case the lower edges of the portions (37) of the sideof the shaft between two adjacent plates 'should slope upward from loweredge of the tions (38) of the rear distributing plates (33) which extendbeyond the next plates to the rear, should be at the same level as thenext plate to the rear, in order to secure a uniform downward flow overthe entire cross-section of the char e. This type ofdischarge feec ermay be enclosed in a housing (40) as shown in Figs. 13 and 14 into whichthe drying gases are forced through the inlet pressure pipe (8). Inthiscase a perforated supporting plate (61) is used and the endless belt(59) is also perforated so that the drying gasesmay pass up through thesupporting plate (61) and belt (59) and upward through the charge. Thebelt may be made of any suitable chain or link or screen constructionwith small enough openings so that'the dried material will notrunthrough or blind the openings. This type of discharge feeder may also beused without the enclosing housing as shown in Fig. 7 In this case thebelt (33) is'supported on the bottom (41) of theshaft and enters beneaththe charge through a slot (42) at the rear of the bottom of the shaft.

The sides (43) and top (44) of the discharge passage (45) are extendedso as to prevent excessive leakage of the drying gases through thedischarge opening (46). The drying gases are introduced into the chargethrough the perforated pipes (10) connected with the pressure pipes (8)as previously described. v

Fig. 6 shows a vertical section of a form of my apparatus in which nodischarge feeder is used the discharge being regulated at the end of thedischarge spout (9). This form is not my preferred type as a uniformdownward flow of the charge cannot be secured except in small machines.The drying gases in this form are introduced through the perforatedpipes 10) from the pressure pipe (8). This form may be either circularor-square in cross-section.

For intermittent drying the. simple apparatus shown in Fig. 18 may beused. This consists of a vertical shaft or box (1) of any desired shapein cross-section with a closed bottom (47) and a grating (48) above thebottom, and a ressure (or vacuum) pipe (8) connected wit the open space(5) beneath the grating. The charge is filled into the upper part of theshaft and levelled and air is then forced through the charge from thepressure pipe (5.). (Or may be drawn down through the char e byapplication of suction to the pipe (8). When the charge has been driedit is removed from the grating by any suitable means, such as droppingthe grating and a new charge supplied.

From the foregoing description the operation of my apparatus will beapparent so that an extended description will not be necessary. Tosecure the best results a substan tially continuous feed should besupplied to esa-rec the to of the charge which should preferably l?maintained at ap roximately the same level at all times and asubstantially continuous discharge at a uniform rate should bemaintained. The drying gases should also preferably be supplied at auniform rate and pressure. Good results may also be securedbyintermittent. continuous operation, i. e.,by feeding and discharging atshort intervals with no movement of the charge between providing theintervals are not too long. r The depth of bed and amount of dryinggases and the required pressure and temperature of these will vary witheach materia to be dried agpording to the nature of the material, thesize of the grains, the moisture content, the dificulty of dryin and thedesired drying effect. As previous y noted, the invention is especially.applicable to the drying of material which are dried with difficulty andwhich must be dried with relatively low temperature drying air or gas,such as wheat and other grains.

Having described my invention, what I claim and desire to patent is:

1. The apparatus for drying grains and granular products which consistsof a vertical shaft for containing a bed of such above said material, adischarging-device arranged to-support a such said bed and arranged todischarge such above said material from the bottom of a such above saidbed in such amanner as to secure a substantially uniform downwardmovement of the material in all parts of said bed, means for forcing acurrent of a gaseous medium upward through such above said bed in saidshaft.

2. The apparatus for drying grains and granular products which consistsof a vertical shaft for containing a bed of such above said material,means for feeding such above said material onto the top of such abovesaid bed in said shaft and means for maintaining the top of a such saidbed substantially level; a discharging device arranged to support a suchsaidbed and arranged to discharge such above said material from thebottom of a such above said bed in such a manner as to secure asubstantially uniform downward movement of the material in all parts ofsaid bed, means for forcing a current of a gaseous medium upward throughsuch above said bed in said shaft.

3. The apparatus for continuously drying grains and granular productswhich consists of a vertical shaft for containing a bed of such abovesaid material, means for continuously feeding such above said materialonto the top of such above said bed in said shaft and means formaintaining the top of a such said bed substantially level; a dischargindevice arranged to support a such said be and arranged to continuouslydischarge such above said material from the bottom of a such above saidbed in such a manner as to secure a substantially continuously uniformdownward movement of the material in all parts of said bed, means forcontinuously cal shaft, for containing a bed of such above saidmaterial, which is closed at thebottom and has adischargin devicetherein above said bottom arran e to support a such above said bed anarranged to allow the passage of a current of gaseous medium up throughsaid device in such a manner that said current of gaseous medium will besubstantially uniformly distributed over the entire horizontal sectionof said bed and arranged to discharge such above said material from thebottom of such above said bed in such a manner as to secure asubstantially uniform downward movement of the material in all partsofsaid bed, means for introducing a current of gaseous medium underpressure into the closed space beneath said discharge device, and meansfor removing the such above said. material removed from the bottom ofsuch above said bed from the lower part of said apparatus.

5. The apparatus for drying grains and anular material which consists ofa vertical shaft for containing a bed of such above said material, saidshaft being closed at the bottom, means for feeding such above saidmaterial onto such above said bed in said shaft and means formaintaining the top of'a such said bed substantially level,

a discharging device in said shaft abovesaid closed bottom arranged tosupport a such above said bed and arranged to allow the passage of acurrentof gaseous medium up through said device in such a manner thatsaid current of gaseous medium will be substantially uniformlydistributed over the entire horizontal section of said bed and arrangedto discharge such above said ma terial from the bottom' 'of such abovesaid bed in such a manner as to secure a substantially uniform downwardmovement of the material in all parts of said bed, means for introducinga current of gaseous medium under pressure into the closed space beneathsaid discharge device, and means for removing the such above saidmaterial removed from the bottom of such above said bed from the lowerpart of said apparatus.

6. The apparatus for continuously drying grains and granular materialwhich consists of a vertical shaft for containing a bed of such abovesaid material, said shaft being closed at the bottom, means forcontinuously feeding such above said material front of said shaft.

onto such above said bed in said shaft and means for maintaining the topof a such said bed substantially level, a discharging device in saidshaft above said closed bottom arranged to support a such above said bedand arranged to allow the passage of a current of gaseous medium upthrough said device in such a manner that said current of gaseous mediumwill be substantially uniformly distributed over the entire horizontal'section of said bed and arranged to continuously discharge such abovesaid material from. the bottom of such above said bed in such a manner;as to secure a s'ub-' stantially continuously uniform downward movementof the material in all parts of said bed, means for continuouslyintroducing a current of gaseous medium under pressure into the closedspace beneath said discharge device, and means for continuously removingthe such above said material removed from the bottom ofsuch above saidbed from the lower part of said apparatus.

7. The apparatus for securing a substantially uniform downward movementof the material in all parts of a bed of material in a vertical shaftwhich consists of an endless belt feeder beneath said shaft, andarranged to support the material in said shaft, with transverse verticalplates above said belt and extending across said shaft and spaced atsubstantially equal distances apart from the back of said shaft to thedischarge opening in the front of said shaft and having their loweredges in a sloping plane extending from the lower edge of the back ofthe shaft at the belt to the upper ed e of the discharge opening in thefront of t e shaft.

8. The apparatus for securing a substantially uniform downward movementof the material in all parts of a bed of material in a vertical shaftwhich consists of an endless belt-feeder beneath said shaft, andarranged to support the material in said shaft with transverse verticalplates above said belt and extending across said shaft and spaced atsubstantially equal distances apart from the back of said shaft to thedischarge opening in the front of said shaft and aving their lower edgesin a sloping plane extending from the lower edge of the back of theshaft at the belt to the '11 per edge of the discharge opening in therout of the shaft, with means for causing the movement of the upper artof said belt from the back of said sha to the discharge In testimonywhereof I' have signed my name to this specification.

Y NIELS C. CHRISTENSEN.

